Decreased numbers of CD4+ T lymphocytes in peripheral blood after treatment of childhood acute lymphoblastic leukemia

Treatment-related immunosuppression in patients with acute lymphoblastic leukemia (ALL) is associated with increased susceptibility to infectious diseases, also after the treatment. The aim of the present study was the detailed evaluation of T lymphocyte subsets in peripheral blood in children after treatment of ALL. All children were treated according to the BFM 90 protocol. The patients were divided into 5 groups of 30 children in each, depending on the time from cessation of the ALL treatment. A control group consisted of 30 healthy children subjected to elective "1-day" surgery. The children's age ranged from 6 to 18 years. The examinations were performed in FACScan flow cytometer with the use of wide set of monoclonal antibodies: CD3, CD4, CD8, TCRalphabeta, TCRgammadelta, CD19, CD25, CD45RA, CD45RO, CD69, HLA-DR, CD16 and CD56, which particularly allowed detailed analysis of T lymphocytes. The results showed that most parameters in children 1 year after ALL treatment completion were similar to healthy children. However, we observed persistently low CD4+ T cell numbers, both CD45RA+ as well as CD45RO+ subsets as compared to the control group. This might reflect decreased regenerative potential of immunological system in children 1 year after ALL treatment.     

Differentiation of leukemic cells induced by short-course high-dose methylprednisolone in children with different subtypes of acute myeloblastic leukemia.

Differentiation of myeloid leukemic cells to mature granulocytes by high-dose methylprednisolone (HDMP, 20-30 mg/kg/day) with a favorable antileukemic effect has previously been demonstrated in children with acute promyelocytic leukemia and acute myeloblastic leukemia (AML) M4. In the present study, three children with other morphological subtypes of AML (two AML M1, one AML M2) were given methylprednisolone (30 mg/kg/day) orally in a single dose. After a short-course (3 or 7 days) of HDMP treatment alone, a striking decrease in blast cells associated with an increase in maturing and abnormally nucleated polymorphonuclear-like cells some containing Auer rods were detected in all patients in peripheral blood or bone marrow smears. During HDMP treatment, in parallel to morphological improvements, marked increases in the percentage of cells expressing granulocytic antigen (CD15) were observed. The increase of CD15 expression on myeloid cells, together with the steady expression of CD34 and CD117 antigens in Casel(AML M1) , is suggestive of aberrant CD34 + CD117 + CD15 + cells, which may indicate the leukemic origin of the maturing myeloid cells. These results suggest that HDMP treatment may induce differentiation of myeloid leukemic cells in some children with different morphological subtypes of AML, and that the differentiation-inducing effect of HDMP should be explored in other malignant diseases.     

Numbers and cytotoxicities of CD3+CD56+ T lymphocytes in peripheral blood of patients with acute myeloid leukemia and acute lymphocytic leukemia

Recent reports have highlighted the role of cellular immunity in anti-tumor defenses. T lymphocytes are known to play important part in anti-cancer immunity. The number and function of T lymphocytes are altered in chronic leukemia patients. CD3⁺CD56⁺ T lymphocytes have also been found to be abnormal in cancer patients. We therefore investigated changes in the number and cytotoxicity of CD3⁺CD56⁺ T lymphocytes in the peripheral blood of acute leukemia (AL) patients (excluding acute promyelocytic leukemia), to improve our understanding of the role of this T lymphocyte subset. We analyzed CD3⁺CD56⁺ T lymphocyte numbers and cytotoxicities in healthy controls, AL patients, and AL patients with complete remission. Lymphocyte counts were performed in peripheral blood and flow cytometry was used to determine cell numbers and cytotoxicities. The absolute number of CD3⁺CD56⁺ T lymphocytes was increased in AL patients (including acute myeloid [AML] and acute lymphocytic leukemia [ALL]) compared with healthy controls (P < 0.05), but their functioning was significantly reduced (P < 0.05). The number of CD3⁺CD56⁺ T lymphocytes in AML and ALL patients who achieved remission following chemotherapy was close to healthy controls (P > 0.05), but their functioning was still significantly reduced (P < 0.05). In addition, the number of CD3⁺CD56⁺ T lymphocytes increased significantly in AML patients with increased peripheral blood white blood cell (WBC) counts, and in ALL patients without increased WBCs. These results suggest that cellular immunity may respond to AML and ALL, but that lymphocyte cytotoxicity remains impaired. Dysfunction of CD3⁺CD56⁺ T lymphocytes in AML and ALL patients may contribute to the failure of the host immune response against leukemic blasts.     

Decrease in number of CD16(Leu 11)+CD45RA(2H4)+ cells and defective production of natural killer cytotoxic factor in childhood acute lymphoblastic leukemia.

CD16 or CD45RA is known to be a functional molecule, which provides activation signals in natural killer (NK) cells or T cells, respectively. To dissect the decreased NK activity in childhood acute lymphoblastic leukemia (ALL), the expression of CD16 (Leu 11) or CD45RA (2H4) and the production of natural killer cytotoxic factor (NKCF) were investigated. CD16+ cells or CD45RA+ cells in peripheral blood lymphocytes were not decreased as compared with controls, however, CD16+CD45RA+ cells in ALL (4%) were lower (p less than 0.05) than controls (17%). The production of NKCF in ALL patients (9.2%) was lower (p less than 0.05) than controls (16.5). These data suggest that the decreased NK activity in ALL patients can be attributable at least in part to the functional impairment of NK cells to produce NKCF.     

Long-lasting decrease of CD4+/CD45RA+ T cells in HCL patients after 2-chlorodeoxyadenosine (2-CdA) treatment.

The CD45RA and CD45RO isoforms of the leukocyte common antigen identify functionally distinct CD4+ T cell subsets: CD4+/CD45RA+ cells which represent a more 'naive' stage of T cell compartment and CD4+/CD45RO+ 'memory' cells. Phenotypic and functional abnormalities in T cell compartment have been frequently reported in patients with hairy cell leukemia (HCL) and, in more recent studies, a significant reduction in the absolute number of CD4+ lymphocytes bearing the CD45RO antigen has also been recorded. In our study we evaluated the CD45RA and CD45RO expression on CD4+ T cells by three-color staining in flow cytometry in 38 HCL patients, 19 untreated and 19 previously treated with 2-chlorodeoxyadenosine (2-CdA), administered at a daily dose of 0.1 mg/kg c.i. for 7 days. In HCL untreated patients, the proportion and the absolute number of CD4+/CD45RA+ and of CD4+/CD45RO+ T cell subsets were similar to normal controls. In contrast, HCL patients at 3-5 years by the end of treatment with 2-CdA, together with a reduction in the absolute number of CD4+ T cells, showed a persistent and significant decrease in the proportion and absolute number of CD4+/CD45RA+ cells as compared with both untreated HCL patients and normal controls (41 +/- 16% vs 57 +/- 14% and vs 65 +/- 7%) (P = 0.01 and 0.0001) and (0.201 +/- 0.137 x 10(9)/l vs 0.549 +/- 0.238 x 10(9)/l and vs 0.696 +/- 0.078 x 10(9)/l) (P = 0.00009 and P = 0.00001). In addition, together with the reduction of CD4+/CD45RA+ cells, we recorded a concomitant increase in the proportion of the CD4+/CD45RO+ cells as compared to untreated HCL patients and normal controls (62 +/- 16% vs 47 +/- 15% and vs 42 +/- 12%) (P = 0.08 and 0.02). These findings may suggest that CD4+/CD45RA+ cells are more sensitive than CD4+/CD45RO+ to the toxic effect of 2-CdA.     

Impact of topotecan-based chemotherapy on the immune system of advanced ovarian cancer patients: an immunophenotypic study

The effects of topotecan-based chemotherapy (CT) on peripheral blood lymphocyte (PBL) subsets were evaluated in ovarian cancer patients. Fourteen patients with epithelial ovarian cancer, at the diagnosis or relapsed after platinum-based CT, were treated with: a) topotecan in association with carboplatin and taxanes as first line CT; b) topotecan alone or c) topotecan in association with carboplatin both as second line of treatment after platinum. The phenotype of PBL was determined before starting treatment and immediately before each CT course by flow cytometric analysis. Before starting CT, the absolute number of lymphocytes and the CD2+, CD3+, CD4+ subsets were significantly lower in pre-treated patients and not significantly altered in CT-naive patients with respect to a cohort of 20 healthy donors utilized as control. Lymphocytes co-expressing CD4+/CD8+ were significantly higher in both subgroups of patients than in normal donors. CD4+/CD45RA+ and CD4+/CD45RO+ subsets were significantly decreased in pre-treated patients and normal in CT-naive patients. CD3+/HLA-DR+ T cell population significantly increased in CT-naive patients at baseline. During CT and after its discontinuation, no relevant changes were recorded for both subgroups of patients with respect to the baseline in lymphocyte absolute count, CD2+, CD3+, CD4+, CD4+/CD45RO+ subsets, while CD4+/CD45RA+ subpopulation was significantly decreased in CT-naive patients. CD8+, CD19+, CD20+, CD16+, CD56+, CD2+/CD25+ subsets did not differ statistically comparing to normal donors both at baseline and during CT. The treatment was well tolerated and no patient developed non-neutropenic infection. Topotecan-based therapy does not have a negative impact on PBL in either CT-naive or in pretreated ovarian cancer patients. This information should be considered when utilizing topotecan with other anticancer drugs in the adjuvant setting as well as when dose-intensification of topotecan with stem cell support is planned.     

The effect of high-dose methylprednisolone treatment on GM-CSF level in children with acute leukemia: a pilot study.

High-dose methylprednisolone therapy (HDMP) induces acceleration of leukocyte recovery in acute lymphoblastic leukemia (ALL) and the differentiation of myeloblasts to mature granulocytes in acute myeloblastic leukemia (AML). These effects of corticosteroids have been shown to be due to the enhanced colony-stimulating activity (CSA) and responses to corticosteroids in some patients with aplastic anemia and myelodysplastic syndromes (MDS) have been related to increased CSA activity. We measured the serum (granulocyte-macrophage colony-stimulating factor (GM-CSF) levels by a sandwich linked immunoabsorbent assay (ELISA) in patients with ALL and AML at presentation and following high-dose methylprednisolone (HDMP) therapy. Serum GM-CSF levels at presentation in the ten cases studied ranged between 160 and 700 pg/ml (mean 418.5 +/- 252.5). One week following HDMP therapy GM-CSF levels increased to between 260 and 950 pg/ml (733.5 +/- 203.2). Four weeks after therapy the GM-CSF levels increased to between 470 and 1350 pg/ml (911 +/- 278.7). GM-CSF levels were markedly elevated one week after HDMP in the patients with ALL, suggesting that in addition to the lymphotoxic effects on leukemic blasts, the acceleration in neutrophil recovery may be due to release of GM-CSF induced by HDMP and its effects on myeloid progenitors.     

The potential effect of short-course high-dose steroid on the maturation and apoptosis of leukemic cells in a child with acute megakaryoblastic leukemia

High-dose methylprednisolone (HDMP) treatment has been shown to induce differentiation of myeloid leukemic cells in children with acute promyelocytic leukemia and other subtypes (FAB AML M1-M2-M4) of acute myeloblastic leukemia. In the present study, a child with acute megakaryoblastic leukemia (AMKL) was given HDMP (30 mg/kg/day) orally in a single dose for the first 4 days of induction therapy. A marked decrease in peripheral blood blast cells and an increase in platelet count associated with a striking change in bone marrow (BM) morphology was observed following a short-course of HDMP treatment alone. BM cells developed distinct morphology characterized by cytoplasmic blebbing and some appeared as platelet producing micromegakaryocytes. Flow cytometric analysis of the BM cells 4 days after HDMP treatment demonstrated a decrease in the percentage of cells co-expressing CD34 and CD117 antigens and a marked increase in CD42a antigen. These changes in BM morphology and immunophenotype may suggest maturation effect of HDMP on megakaryocytic leukemic cells. In addition ultrastructural analysis of BM cells cultured with methylprednisolone (10(-3) and 10(-6) M) for 24 and 48 h showed numerous apoptotic cells. This was coincident with a significant increase in the percentage of annexin positive cells. These results suggest that HDMP treatment may induce differentiation and apoptosis of leukemic cells in a child with AMKL and it could be a promising agent for remission induction of patients with AMKL.     

The expression pattern of CD56 (N-CAM) in human bone marrow biopsies infiltrated by acute leukemia

In hematological neoplasms CD56 (N-CAM) is expressed by T/natural killer (NK) cell lymphoma, by most neoplastic plasma cells in multiple myeloma and also in a subset of acute myelogenous leukemias (AML). In the latter, it is an indicator of poor clinical outcome. Most of the data on CD56 expression in acute leukemia have been obtained by flow cytometric analysis. Up to now, no systematic analysis of the expression pattern of CD56 in formalin fixed paraffin embedded bone marrow biopsies of acute leukemias has been performed. We immunohistochemically studied the expression of CD56 in a series of 141 bone marrow biopsies fixed in Sublimat Mercury II Chloride (SUSA) including 100 cases of AML FAB M0-M7, 11 cases of AML not further specified, 3 cases of biphenotypical leukemia, 20 cases of acute lymphoblastic leukemia (ALL) and 7 cases of reactive bone marrow biopsies. Overall, 14 of 134 (10%) leukemia cases were positive for CD56. Detail analysis revealed positivity in 5/13 cases of AML M5 (38%), 3/9 AML M1 (33%), 1/8 AML M0 (13%), 1/11 AML not specified (9%), 2/31 AML M2 (7%) and 2/26 AML M4 (8%). All cases of ALL and biphenotypic leukemias were CD56 negative. The CD56 expression in AML M5 was statistically significant (p=0.003). On paraffin embedded bone marrow biopsies CD56 expression occurs in de novo AML with an overall frequency of 13%. It is significantly correlated with AML M5, which is positive in 38% of the cases. Cases of ALL are consistently CD56 negative.     

恶性血液病患者化疗前后淋巴细胞亚群测定及其意义

 目的 研究恶性血液病患者化疗前后淋巴细胞亚群的变化及其意义。方法 采用流式细胞术对21例急性淋巴细胞白血病（ALL）／非霍奇金淋巴瘤（NHL）患者和23例急性髓系白血病（AML）患者化疗前后淋巴细胞亚群（包括CD+4细胞、CD+8细胞、CD+4／CD+8比值、NK细胞）进行检测。结果 CR组白血病、淋巴瘤的CD+4／CD+8与NK细胞比例均明显高于初诊组和化疗后未缓解组白血病、淋巴瘤（P＜0.05）;CR组ALL／NHL的CD+4／CD+8明显低于CR组AML（P＜0.05）。结论 CD+4／CD+8与NK细胞比例可以作为判断恶性血液病患者病情严重程度和预后的指标,与AML相比,ALL／NHL的细胞免疫功能受损更为严重。     

Clinical Significance of Co-expression of Aberrant Antigens in Acute Leukemia: A Retrospective Cohort Study in Makah Al Mukaramah,Saudi Arabia

Background: Aberrant phenotypes in acute leukemia have variable frequency and their prognostic andpredictive relevance is controversial, despite several reports of clinical significance. Aims: To determinethe prevalence of aberrant antigen expression in acute leukemia, assess clinical relevance and demonstrateimmunophenotype-karyotype correlations. Materials and Methods: A total of 73 (40 AML and 33 ALL) newlydiagnosed acute leukemia cases presenting to KAMC, Kingdom of Saudi Arabia, were included. Diagnosis wasbased on WHO criteria and FAB classification. Immunophenotyping by flow cytometry, conventional karyotypingand fluorescence in situ hybridization for gene rearrangements were performed. Results: Aberrant antigens weredetected in 27/40 (67.5%) of AML and in 14/33 (42.4%) in ALL cases. There were statistically significant higherTLC in Ly+ AML than in Ly-AML (p=0.05) and significant higher blast count in ALL with aberrant antigensat presentation and day 14 (p=0.005, 0.046). There was no significant relation to clinical response, relapse freesurvival (RFS) or overall survival (p>0.05), but AML cases expressing ≥2 Ly antigens showed a lower medianRFS than those expressing a single Ly antigen. In AML, CD 56 was expressed in 11/40. CD7 was expressed in7/40, having a significant relation with an unfavorable cytogenetic pattern (p=0.046). CD4 was expressed in 5/40.CD19 was detected in 4/40 AML associated with M2 and t (8; 21). In ALL cases, CD33 was expressed in 7/33and CD13 in 5/33. Regarding T Ag in B-ALL CD2 was expressed in 2 cases and CD56 in 3 cases. Conclusions:Aberrant antigen expression may be associated with adverse clinical data at presentation. AML cases expressing≥2 Ly antigens may have shorter median RFS. No specific cytogenetic pattern is associated with aberrant antigenexpression but individual antigens may be related to particular cytogenetic patterns. Immunophenotype-karyotypecorrelations need larger studies for confirmation.     

Having a higher blast percentage in circulation than bone marrow: clinical implications in myelodysplastic syndrome and acute lymphoid and myeloid leukemias.

Determining the percentage of peripheral blood (PB) and bone marrow (BM) blasts is important for diagnosing and classifying acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). Although most patients with acute leukemia or MDS have a higher percentage of BM blasts than PB blasts, the relative proportion is reversed in some patients. We explored the clinical relevance of this phenomenon in MDS (n = 446), AML (n = 1314), and acute lymphoblastic leukemia (ALL) (n = 385). Among patients with MDS or ALL, but not AML, having a higher blast percentage in PB than in BM was associated with significantly shorter survival. In multivariate analyses, these associations were independent of other relevant predictors, including cytogenetic status. Our findings suggest that MDS and ALL patients who have a higher percentage of PB blasts than BM blasts have more aggressive disease. These data also suggest that MDS classification schemes should take into account the percentage of blasts in PB differently from the percentage of blasts in BM.     

Detection of acute leukemia cells with mixed lineage leukemia (MLL) gene rearrangements by flow cytometry using monoclonal antibody 7.1.

Translocations involving 11q23 are among the most common genetic abnormalities in hematologic malignancies, occurring in approximately 5-10% of acute lymphoblastic leukemia (ALL) and 5% of acute myeloblastic leukemia (AML). In 11q23 translocations, the mixed lineage leukemia (MLL) gene on chromosome 11, band q23, is usually disrupted. The human homologue of the rat NG2 chondroitin sulfate proteoglycan molecule, as detected by the monoclonal antibody (moab) 7.1, was shown to be expressed on leukemic cells with MLL rearrangements of children with acute leukemia. We further investigated the reactivity of the moab 7.1 on 533 cell samples of adults (n = 215) and children (n = 318) with acute leukemias (271 AML, 217 B-lineage ALL, 37 T-lineage ALL, eight CD7+ CD56+ myeloid/natural killer cell precursor acute leukemias) by flow cytometry. In AML, 38 samples were positive for moab 7.1 ('20%-cut-off-level'). These moab 7.1-positive AML cases revealed a myelomonocytic-differentiated immunophenotype with coexpression of the NK cell marker CD56 in 33 of 38 cases. Two of eight cell samples of the recently described CD7+ CD56+ myeloid/natural killer cell precursor acute leukemia entity reacted with moab 7.1. In ALL, 35 samples mostly of the pro-B-ALL subtype (33 pro-B-ALL, one common-ALL, one pre-B-ALL) were positive for moab 7.1. 58 (81%) of 72 samples with MLL rearrangements were positive for moab 7.1 including 28/31 with a t(4;11), 16/17 with a t(9;11), 3/5 with a t(11;19), and 2/6 with a del(11)(q23). All moab 7.1-positive ALL (n = 34) and childhood AML (n = 17) cases revealed MLL rearrangements as detected by Southern blot analysis and RT-PCR. However, 11 adults with AML, and one adult with moab 7.1-positive CD7+ CD56+ myeloid/natural killer cell precursor acute leukemia were negative for MLL rearrangements as proved by Southern blot analysis. We conclude that moab 7.1 is a sensitive but not entirely specific marker for the identification of 11q23-associated AML and ALL by flow cytometry in children and adults.     

Expression of N-CAM (CD56) on Acute Leukemia Cells: Relationship with Disease Chracteristics and Outcome

Expression of CD56 was analyzed by indirect immunofluorescence method on bone marrow samples from 94 newly diagnosed patients with acute leukemia (AL), including 59 acute myelogenous leukemias (AML) and 35 acute lymphoblastic leukemias (ALL). CD56 was expressed on 17 f 18% (range: 0-728) of AML cells and 24 f 248 (range: 0-988) of ALL cells. without significant diffcrences between FAB subtypes in AML, nor immunologic subtypes in ALL. Expression of CD56 was not associated with any clinical or biological characteristic at diagnosis, nor with prognosis in AML or ALL. We do not confirm previously described relationships between CDS6 expression and initial characteristics and evolution of acute leukemia.     

The effect of steroid on myeloid leukemic cells: the potential of short-course high-dose methylprednisolone treatment in inducing differentiation, apoptosis and in stimulating myelopoiesis

Several in vitro studies have shown that dexamethasone (Dex) and prednisolone can induce differentiation of some mouse and human myeloid leukemic cells to macrophages and granulocytes. Based on in vitro experiments, we have shown that short-course (3-7 days) high-dose methylprednisolone (HDMP) (20-30 mg/kg/day) treatment can induce differentiation of myeloid leukemic cells in vivo in children with different subtypes of acute myeloblastic leukemia (AML) (AML-M1, -M2, -M3, -M4, -M7). We have also shown that induction of apoptosis of myeloid leukemic cells with or without differentiation is possible by short-course HDMP treatment. In addition, short-course HDMP treatment has been shown to be effective in accelerating leukocyte recovery, possibly stimulating normal CD34-positive hematopoietic progenitor cells. Addition of HDMP to mild cytotoxic chemotherapy (low-dose cytosine arabinoside (LD-Ara-c), weekly mitoxantrone and Ara-c or 6-thioguanine) increased the remission rate (87-89%) and improved the outcome of AML children. We believe that the results of our 17-year clinical experience will provide important benefits to AML patients.     

68例成人白血病免疫分型特点分析

[目的]分析68例成人白血病免疫分型特点.[方法]采用单克隆双色或三色直接荧光标记,流式细胞仪检测以CD45-SSC辅助设门,分型根据抗体积分系统.并与FAB分型进行比较.[结果](1)62例成人白血病中未分化型占6.45%(4例),变异型占12.9%(8例).其中急性髓细胞白血病(AML)占69.35%(43例),B细胞型急性淋巴细胞白血病(B-ALL)占16.13%(10例),T细胞型急性淋巴细胞白血病(T-ALL)占6.45%(4例),AML/ALL为3.07:1.CD34的阳性率在62例成人急性白血病和6例慢性粒细胞性白血病急变患者中分别为58.06%和83.33%;免疫分型与FAB分型的符合率为83.9%.[结论]在流式细胞仪上采用CD45-SSC设门法多参数分析白血病免疫分型,并利用抗体积分系统诊断标准可为临床诊断提供重要依据.     

All-Trans Retinoic Acid (ATRA) and the Regulation of Adhesion Molecules in Acute Myeloid Leukemia

A review of recent information on the expression and the ATRA-driven modulation of cell surface adhesion molecules of acute myelogenous leukemia blast cells is presented. Cytofluorometric studies on fresh blast cells have demonstrated that CD11a, CD11b, CD11c, CD15, CD45RO and CD54 expression is significantly lower in acute promyelocytic leukemia (APL) than in acute myeloid leukemia of other subtypes (AML). In vitro treatment with ATRA dramatically modifies the adhesion phenotype of APL blast cells, promoting a consistently striking up-regulation of CD11b, CD11c, CD 15, CD65, CD54 and CD38. Which is, in general, poorly demonstrable in AML. The behaviour of CD15s is variable and fully independent from CD15 and CD65 in induction experiments, suggesting a differential enzymatic regulation within the selectin ligand system. ATRA is capable, in both APL and AML, of producing a switch from the high- (RA) to the low- (RO) molecular weight isoform of CD45. Moreover, treatment with this retinoid exerts a negative regulation of the membrane expression of CD49e, CD58 and CD11a in APL as well as in AML. Of particular interest is the fact that the negative effect on CD11a expression generates an asynchronous phenotype in APL (CD11a-, CD11b+, CD 15+), undetectable on normal maturing myeloid cells.

In the last part of this review the possible implications of adhesion molecule modulation in the pathogenesis of ATRA syndrome are discussed.     

Interpretation of interleukin-2 receptor alpha positive cells during induction chemotherapy for adult acute myelogenous leukaemia patients

To correlate clinical outcomes with the expression of interleukin-2 receptor alpha (CD25) positive cells during induction chemotherapy (IC) in adult patients with acute myeloid leukaemia (AML), we investigated the prognostic importance of subsets of peripheral blood (PB) CD45+CD25+ cells. Seventy-five patients with newly diagnosed AML received the same initial IC; and serial PB samples were taken. The gated CD45/CD25 cell populations were used to compare the intensity of immunophenotypic signals based on the treatment timeline. Patients who responded poorly to IC demonstrated exceptionally higher levels of PB CD45+CD25+ cells by percentage (p = 0.003) or by absolute count (p = 0.046) on the seventh day (D + 7) of initial IC. In addition, patients in complete remission (CR) (n = 61) demonstrated relatively lower levels of steady PB CD45+CD25+ after standard IC. These results suggest that the expression of CD25 can be used to predict the response to IC during an early period of treatment.